The Los Azufres (México) Geothermal Reservoir: Main Processes Related to Exploitation (2003-2011)

Abstract

In this work the present-time thermodynamic conditions and the response to exploitation for 2003-2011 of the Los Azufres geothermal reservoir are given. The study was based on the analysis of geochemical and production data of 39 wells, over time. In average, due mainly to effective reservoir recharge, very moderate production declining rates were found. In the south zone the important effects of reinjection are seen through increases in Cl in some wells (up to 8,000 mg/kg). In contrast, in wells with significant boiling Cl tends to decrease. In most of the northern zone wells, the variations in gas data indicated boiling and condensation of a highly gas-depleted brine, which seems to consist of reinjection fluids. It is suggested that this process helps to maintain the production in the zone relatively stable. In summary, the main reservoir exploitation-related processes found in Los Azufres were: (1) Production of reinjection returns. For this, it was possible to distinguish (a) wells that produce liquid and steam from injection and (b) wells that produce only steam from injection and sometimes this steam already condensed. (2) Boiling. For this process, two types of boiling were identified: (a) boiling with gaining steam and (b) boiling with steam loss.